Electromagnetic brake apparatus.



A. SUNDH. ELECTROMAGNETIC BRAKE APPARATUS.

APPLIQATION FILED OUT. 2, 1907.

Patented May 31, 1910.

v 5 2 3 2 4 F F F a 4 3 I I fl 6 490 7 y 1% a 4? 2M ,ZW V y /C w W 4% #2 9 m a 4 0 O U 9 m z w 0 o 0 7 7 UNITED STATES AUGUST SU NDH, OF YONKERS, NEW YORK, ASSIGNOR TO OTIS ELEVATOR COMPANY,

PATENT OFFICE.

OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

ELECTROMAGNETIC BRAKE APPARATUS.v

Specification of Iietters Patent.

Patented May 31, 1910.

Application filed October 2, 1907. Serial No. 395,626.

To all whom it 'may concern:

Be it known that .I, AUcus'r SUNDH, a citizen of the United States, residing in Yonkers, in the county of \Vestchester and State of New York, have invented a new .vision of multiple electro-magnetic mechanism for eflecting the gradual application of a brake.

Another object of the invention is to provide multiple elcctro-magnetic mechanism to quickly release a brake.

Further objects will appear more fully hereinafter, the novel combinations of elements being set forth in the claims.

Referring to the accompanying drawing, Figure l is a front elevational view in part section of a magnetic brake embodying my invention. Figs. 2, 3 and 4 are sectional details of parts shown in Fig. 1.

Similar characters of reference designate corresponding parts in all of the figures.

In substantially all electro-magnetic brake apparatus in use at the present time,

a single magnet of relatively large SlZels used to effect the release of the brake members, and the magnet 18 preterably of the well known solenoid tvpe. Such brake apparatus is objectionable for the reason that it is sluggish in its releasing action, and when the same is deenergized the brake is immediately applied with maximum pressure. 1 i

A magnet brake constructed according to my invention notonly withdraws the brake shoes very quickly, but etl'ectsthe application of the brake in such manner that the braking effect is gradually increased from For example, .it may be fixed on the armature shaft 4 of an electric motor.

8 and 8 designate brake members which maybe of any suitable construction and which when applied to the part 3 tend to stop the latter from rotating. As here shown the brake members 8, 8' are in the form of shoes. The brake shoes 8 and 8 are arranged to be withdrawn or released from the brake pulley 3 by electro-magnetic means, and the electro-magnetic means is arranged when deprived of its exciting current to permit the brake shoes to be gradu ally applied to the brake pulley 3.

5 and 5 are brake levers pivoted at 6 and -6', respectively, to the frame 1 carried upon a bed 2. Each brake lever-is provided with brake shoes 8. and 8', respectively, which are .pivoted at 7 and 7 to the brake levers 5 and 5 and which are held in proper rela- I tiorto the brake pulley 3 by the springs 9 an 9. shoes may be faced with leather or other suitable material if desired, and such facing is indicated on the drawing by heavy black lines. A rod 30 is connected to the brake lever 5 at 31 and'passes' loosely through a clearance hole in the brake lever 5'. A compression spring 33 is carried upon the rod 30 and bears against thevbrake lever 5' and a collar 34, which latter is adjustable along the rod 30 by means of the nuts-32. By adjusting these nuts the tension of the spring may be varied as desired. a 1 Attached to the frame 1 are electro-magnets of the solenoid type, namely, 10, 11 and 12. These magnets are preferably of different sizes, the magnet 10 being the smallest, the magnet 11 somewhat larger, while the magnet 12 is still larger. This arrangewinding 10' and these cores are connected The engaging facesof'thc brake to recessed collars 17 and 17 ',-respectively,

by screw-threaded rods 16 and 16, adjustable in correspondingly threaded openings in the cores. A pair of tension springs 15 and 15' respectively surround the threaded rods 16 and 16' and are placed between the recessed collars 17 and 17' and some fixed part of the apparatus, for example the opposite ends of the frame of magnet 10. A washer 13 of leather or other suitable material is provided at the center of the solenoid and lies midway between the cores 1.4 and 14:. The lever arms 5 and 5 are provided with pointed set screws 18 and 18', respectively, which are in horizontal alinement with the magnet cores 14 and 14'. The pointed end of each setscr'ew hes in a recess provided in the collars 17 and 17' and each set screw may be individually adjusted and locked in position by the nuts 19 and 19. The magnet 11, as before stated, is substantially similar in constructlon to the magnet 10 just described, although somewhat larger in size. The cores of this magnet lie closer together when the brakes are applied'than do the cores of the magnet 10, and thewasher 20 is somewhat thinner than the washer 13. The distance between the inner ends of the cores allows for movement of the brake levers. The cores of the magnet 12 lie still closer together when the brakes are applied, and in this magnet I do not purpose to use any washer. Referring to Flgs. 2, 3 and 4, the different constructions of the magnet cores is readily seen. The cores 14 and 14; each contain four slots uniformly spaced, and which are preferably. cutin the cores on planes some What removed from the axes of the cores. The cores of the magnet 11 each contain two similar slots arranged diametrically opposite each other. The cores of the magnet. 12 do not contain slots, but are left solid. The slots counteract eddy currents and the magnet having the core with the greatest number of slots will act quicker both in actuating and releas1ng.

The solenoid windings of the magnets 10, ,11 and; 12 are connected in parallel with each other, each having its terminals connected to the main wires 38 and 39, respectively, which in turn are connected through the switch 37 to a suitable source of electrical supply designated by and The spring 33 tends to force the upper ends of the brake levers 5 and 5 together and thereby move the brake levers about their respective pivots 6 and 6, and thus Withdraw the brake shoesS and 8 from en agement with the periphery of the brake pulley 3. This tendency, however, is more than overcome by the combined action of the springs 15, 22, EEG and 15, 22, 26' and the brake is applied with maximum pressure.

In order to release the brake shoes and allow the rotating member 3 to turn, the

switch 37 is closed, thereby connecting all of the brake magnets 10, 11 and 12 simultaneously to the source of current supply and and the same are energized to move their respective cores together against the action of the various springs connected therewith. Since the magnet 10 is farthest removed from the pivots 6 and 6 of the corresponding brake levers 5 and 5', the cores of this magnet will have a relatively long movement indicated on the drawing by the length of air gap between the cores 14 and 14'. The magnet 11 is somewhat nearer the pivots 6 and 6 and the leverage or mechanical advantage of this magnetwith respect to the magnet 10 is not so great, consequently the movement of its cores will be smaller and the air gap between the cores of this magnet will also be smaller. The magnet 12 being nearest the pivots 6 and 6 will have the smallest air gap of all.

The washers 13 and 20 which lie between the corcs of the magnets 10 and 11,

respectively, not only space the cores when in their energized position but also act as cushions or buffers to prevent noise. As the different magnets become energized their cores are drawn together, compressing the springs at both ends of each magnet and permitting the sprin 33 to move the upper ends of the brake levers together, which effects the release of the brake shoes 8 and 8 from engagement with the brake pulley 3.

It is well known that a small magnet will become energized to operate its core or movable member upon closing a circuit. through its magnetizing coil much quicker than a similar magnet of larger size. -This is largely due to the smaller amount of magnetic material comprised in the smaller magnet in which the effects of self-induction are relatively small. The greater the inductance, the greater the time constant of the magnet. Thus it is readily seen that by using a plurality of brake-releasing magnets suitably connected to the current supply mains, the same build up in magnetic strength and effect the operation of their cores much quicker than would a single magnet of large size, and it is an easy matter to so arrange the plurality of magnets that their operation may be substantially.

of the braking means the motor is enabled to start at substantially the same instant that the motor circuit is closed, thus avoiding useless waste of starting current and undue strain upon the hoisting apparatus.

In order to apply the brakes the main switch 37 is first opened, thereby interrupting or cutting off the current supply to the windings of the brake magnets. The cores of magnet will be the first to return to their deenergized position, being moved outwardly by the springs and 15, and the recessed collars 17 and 17 will abut against the set screws 18 and 18', respectively, and

' force the upper ends of the brake levers 5, 5'

outwardly, overcoming the action of the spring 33 and gently applying the brake shoes 8, 8 to the pulley 3. The cores of magnet 10 will operate before the cores of the magnets 11 and 12 because of the slots 35 in its cores 14: and 14, as these slots tend to counteract the retarding effects of eddy currents in the core. Furthermore, the magnet 10 has a smaller number of turns and its self-induction for that reason is less than that of the magnets 11 and 12. Thus the springs 22 and 22 will force the recessed collars 23 and 23 into engagement with the set screws 24 and 24, respectively, parts a short time after the co'rrespondin of the magnet 10 have performed theirfunctions. The magnet 12 is the last one to act, since the cores of this magnet contain no slots and the self-induction is a maximum. Therefore the springs 26 and 26' of this magnet do not operate to increase the braking efiectmntil after the magnets 10 and 11 have operated.

From the foregoing it is seen that the application of the brake shoes is not effected at once, but a certain degree of braking effect is first produced by the application of one set of springs, shortly afterward followed by the application of an additional set of springs, and finally the maximum braking effect is produced by the application ofa third set of springs. While the consecutive operation of these diflerent sets of springs may take place in a very short space of time, the gradually increasing pressure of the brake shoes upon the brake pulley 3 produces a'smooth and easy stop which is a particularly valuable featurein the eflicient operation of. electric elevators, as well as in many other devices where... an electrically operated brake may be used. The position of any one of the magnet cores may be separately adjusted by means of the corresponding threaded rods, such as 16 and 16', which may be screwed into or out of their respective cores, and the tension of each magnet spring may be regulated by adjusting its corresponding set screw such as 18 and 18'.

While I have shown three brake magnets of varying size for efl'ecting the operation apparatus.

of my brake apparatus, I contemplate using largely uponthe requirements of any particular case. Furthermore, where a plurality of magnets is used, if one should become disabled the remaining magnet or magnets would still be suflicient to operate the brake By placing the magnet first to release nearest the rotating member 4. the leverage on the brake levers as the successive pairs of springs act may be gradually increased. If single phase current is used I prefer to laminate all the cores and core frames and secure successive operation by electric switches controlling the .magnets such that upon the release of the first mag- .net a switch is operated to open the circuit 'of the next magnet, and so on.

While the foregoing description applies to a preferred form of magnetic brake apparatus embodying my invention, I do not Wish to be limited'to the specific construction and arrangement of parts, as it is obvious that various changes could readily be made by those skilled in the art. without departing from the spirit or scope of my invention.

That I claim is 1. The combination with a brake, of meehanism for applying the brake, and a plurality of electro-magnets of different capacities for effecting a release of the brake and each being operative independently of the operation of the other-s. I

2. The comblnatlon in a brake, of a brake lever, a brake shoe, mechanism for operating the brake lever in one direction to apply the brakeshoe to a movable member, and apinrality of electro-magnet-s of varying eapaeities operative in opposition to said operating mechanism.

3. In elect-ro-magnetic brake apparatus. the combination with a brake lever and a brake shoe, of a plurality of electro-magnets of difi'erent inductances operatively connected to the brake lever to control the operation of the same in one direction, and

mechanism for actuating said lever in an-.

other direction.

4. In electro-magnetic brake apparatus, the combination with a brake lever and a brake shoe, of mechanism for operating the lever to apply the brake, and a plurality of electro-magnets of varying in'ductances opposing said brake applying mechanism, and of suflicient strength when energized to overcome the power of said applying mechanlsm and permit the release of the brake.

5. In electro-magnetie brake apparatus, the combination with a brake lever, a brake shoe and springs for applying the brake, of a plurality of eleetro-magnets of different inductances connected in parallel circuits, and switch mechanism for controlling said electro-magnets.

. terposed between the magn 6. In electro-ma etic brake apparatus, the combination with a brake lever and a brake shoe, of a plurality of electro-magnets and springs opposing the operation of the electro-ma nets and operating upon said lever at di erent distances from its fulcrum.

7. In eleotro-ma etic brake apparatus, the combination with a brake lever and a brake shoe, of a plurality of electro-magnets of different strengths in position'to control the operation of the lever and located at distances from the fulcrum of the lever,

varying inversely as the strength of the magnets.

8. In electro-magnetic brake a paratus, the combination of a pair of ivo ed brake levers and brake shoes carried y the levers, and a plurality of electro-magnets located between said levers and of a strength and inductance substantially inversely proportional to their distances from the fulcrums of the levers.

9. In electro-magnetic brake apparatus, the combination with a brake lever, of a plurality of electro-magnets, each comprising a frame and a magnetic, core or armature, extensions from said cores, springs inet frames and said' extensions to hold the latter in their outward positions against thebrake lever when the magnets are deenergized, and means for moving the lever inwardly when the extensions are retracted by said electromagnets.

10. In electro-magnetic brake apparatus, the combination with a pair of brake levers, of a plurality of electro-magnets located between the levers at different distances from their fulcrums, and each comprisingvmovable cores, extensions carried by said cores and eugagin the levers, said cores and extensions being moved inward and held in an inward position when the magnets are energized, springs associated with the ex tensions and holding them in an outward position when-the magnets are dee-nergized, and means for moving the levers inwardly as the extensions are drawn inwardly by the magnets.

11. In brake apparatus, the combination vwith a brake shoe and an actuating device connected thereto, of automatic mechanism for applyin the brake shoe to a movable member, a pIurality of electro-magnets with movable cores shaped to effect varying time 1 constants as to said electro-magnets, and connections between said electro-magnets and said levers.

12. In brake apparatus, the combination with brake mechanism, of means for applying the brake, and electro-magnets havmg cores released successively to permit a gradual operation of said brake-applying-means.

l LThe combination with brake mechanism, of a plurality of springs for operat-' ing said brake mechanism to apply the same, and a plurality of electro-magnets to retract a 15. The combination with brake mechanism, of an electro-magnet having a movable core, a cup or plate connected to said core, a spring interposed between the magnet and the said cup, and an adjustable abutment between the cup and said'brake mechanism.

16. The combination with symmetrical brake shoes and symmetrical levers connected thereto, of an electro-magnet between said levers having two cores, extensions from said cores normally in loose connection with said levers, and springs located at opposite ends of the electro-magnet, each spring being located between-the outer end of one of said extensions and the adjacent end of the elec'tro-magnet.

17. The combination with two brake shoes and two levers respectively connected thereto, of a plurality of separate and inde-' pendent springs arranged in pairs and the pairs in a series, a corresponding series of electro-magnets respectively between the said pairs of springs, each electro-magnet having a pair of cores variously shaped to cause the electro-magnets tohave difi'erent time constants or inductances, and extensions from said cores to receive the outer ends of said springs and abut against said levers.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

AUGUST SUNDH. 

